I'm pretty sure some group admins feature every image that is submitted to them. It's really not hard to get more than three features on an image, especially if you belong to many different groups. As to whether or not displaying more icons from those groups under your image would lead to more sales, I haven't a clue, but I'd really doubt it. If someone happens upon your image and isn't already sold on it, will knowing that it was featured in the 'Most General Group of Images Ever' group cause them to pause and reflect on their hasty decision that it wasn't really their style and didn't coordinate with anything in their house? Probably not. And if it won't lead to more sales, why clutter up the page with it? Maybe a list in Behind the Scenes would be nice to help keep track though.